<title>Analysis of gas degradation under a closed-cycle high-repetition-rate operation of a transversely excited atmospheric CO<formula><inf><roman>2</roman></inf></formula> laser</title>

Abstract

Using the newly developed 1 kHz closed-cycle TEA CO2 laser with the efficient CO2 regenerator including the Pt/Al2O3 solid catalyst, we experimentally determined the minimum operational performance of the CO2 regenerator which is required for the stable and long-life operation of the closed-cycle TEA CO2 laser. The operational performance of the CO2 regenerator was evaluated by the fractional conversion (eta) from CO to CO2, which is defined as the ratio of the differential CO2 concentration increased by the CO2 regenerator to the total CO concentration introduced into the CO2 regenerator. The minimum eta of 0.07 was at least required to keep the laser output power at 95 percent of the initial laser output for the laser gas mixture of CO2/N2/He = 15/15/70 (percent) and at an input energy density and a clearing ratio of 150 J/l and 6.0, respectively. When operating the CO2 regenerator at eta of 0.10, no appreciable reduction of the initial laser output of 570 W due to CO2 decomposition was observed up to 1.8 x 10 exp 7 shots (5 hrs). At this time, gas analysis showed that the CO and O2 concentration in the laser gas mixture was maintained about at 0.17 percent and 0.055 percent, respectively.